A CONTINUOUS OIL-WATER SEPARATOR A THESIS IN …
56
A CONTINUOUS OIL-WATER SEPARATOR by AHMED R. VINE, B.S. in Ch.E. A THESIS IN CHEMICAL ENGINEERING Submitted to the Graduate Faculty of Texas Tech University in · Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE IN CHEMICAL ENGINEERING Approved Accepted August, 1974
Transcript of A CONTINUOUS OIL-WATER SEPARATOR A THESIS IN …
A CONTINUOUS OIL-WATER SEPARATOR
by
AHMED R. VINE, B.S. in Ch.E.
A THESIS
IN
CHEMICAL ENGINEERING
Submitted to the Graduate Faculty of Texas Tech University in ·
Partial Fulfillment of the Requirements for
the Degree of
MASTER OF SCIENCE
IN
CHEMICAL ENGINEERING
Approved
Accepted
August, 1974
I\'-
go~s
T3 ) C1'?4-")J I C) I - I (0 I
O~op, 1,
ACKNOWLEDGEMENTS
The author wishes to extend his appreciation to Dr. James E.
Halligan, Committee Chairman, for his guidance and advice. Appre
ciation is also extended to Dr. George F. Meenaghan and Dr. Robert M.
Sweazy for their help in writing this thesis. .
I am deeply indepted to Mr. Ben R. Gunn whose help and advice
made possible all that has been accomplished. Acknowledgement is
also given to Mr. Steven Duffy for making available his literature
collection on the subject and to Mr. David Arnett, Mr. Michael Morris
and Mr. John Liang for their help in obtaining the data; and to
Mrs. Peggy Boyd for editing and typing the manuscript.
The author gratefully acknowledges Cotton Incorporated for pro
viding financial support for this project.
11
TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS . . 11
LIST OF TABLES iv
LIST OF ILLUSTRATIONS v
I. INTRODUCTION 1
II. LITERATURE REVIEW 4
III. EXPERIMENTAL APPARATUS, OPERATING PROCEDURE AND ANALYTICAL TECHNIQUE 11
IV. DISCUSSION OF RESULTS 21
v. CONCLUSIONS AND RECOMMENDATIONS 49
REFERENCES 50
. . . 111
LIST OF TABLES
Page
I. Dimensions of MK II 13
II. Initial Feasibility Test 22
III. Tests with Light Oil Using MK II 26
IV. Effect of Modifying Filter/Coalescer Supports 30
v. Effect of Temperature 33
VI. Breakthrough Point Test 36
VII. Breakthrough Point Test 39
VIII. Effect of Temperature 44
IX. Comparison of Average Values 47
iv
LIST OF ILLUSTRATIONS
Page
1 . Separator 12
2. Oil-water Feed System 14
3. Modified Water Heating System 15
4. Wooden Prototype 3 Compartments 24
5. Effects of Leaks in System MK II-4 Compartments 28
6. Effect of Modifying F11ter/Coa1escer Supports 31
7. Breakthrough Test 42
8. Effect of Temperature 46
v
CHAPTER I
INTRODUCTION
Public awareness of ecological problems has resulted in the
legislation of many anti-pollution laws. These laws, coupled with
the desire of the large corporations to better their public image,
and the prospect of stricter laws in the future have led to a mas
sive effort by both public agencies and private corporations to
develop the technology required to minimize pollution of the environ
ment.
One aspect of pollution which has received wide attention is
the discharge of oil into public waters. Visible oil is objection
able from an aesthetic point of view and it damages recreational
areas. It also detroys marine life by coating algae and plankton,
thereby removing a source of fish food. In addition, these coated
organisms can settle to the bottom destroying spawning areas. Finally
the flavor of fish frequently develops an unpleasant taste due to the
presence of hydrocarbons (9).
In potable waters the presence of even small amounts of hydro
carbons renders an unpleasant taste.
The principal cause of oil pollution in inland waterways and
lakes is the discharge of oily wastewaters from industries. Oil
pollution of the sea and beaches is caused by the discharge of oily
wastewater from industries as well as seepage from offshore drilling
1
2
operations. Other possible causes are the accidental discharges or
release of oil ballast water from ships. Examples of natural seepage
and oil spills from ships' accidents are the Santa Barbara oil spill
and the Torey Canyon disaster, both of which focused world attention
on the problem because of the heavy damage they caused to the environ
ment.
As a result of the intensive research effort in progress across
the nation, a variety of ingenious methods have been proposed and
marketed over the past few years for the separation and removal of
oil from water. As a part of this, Texas Tech University has had a
program for the evaluation of the properties of various materials and
their application to the oil separation and cleanup problem. Interest
has centered on cotton after research showed it to have excellent oil
sorption properties in the raw form and oil-water separation proper
ties in the fabric form.
The development of a continuous rotating drum system in which the
flow was through a belt has been a part of the program at Texas Tech.
After development in the laboratory, this system was subjected to
field trials at El Paso Products Company in Odessa, Texas, and the
Dow Chemical Company in Freeport, Texas. Mechanical problems were a
major drawback with the belt system, but results using cotton terry
towel as belt material were encouraging. These field tests indicated
that an oil-water separator with no moving parts would be more desir
able. This led to this study, which has as its principal object,
3
the development of a static, staged oil-water separator which uses
cotton as a coalescing medium.
CHAPTER II
LITERATURE REVIEW
There are approximately 10,000 oil spills annually in the world
which result in the release of over 10 million gallons of oil to the
environment (8). Assessments of the present state of the art of clean
up technology suggest that over 80% of the oil accidentally discharged
into the environment remains and is never removed. The data are not
clear whether this estimate takes into account oil from chronic sources
of pollution, such as the petroleum refining industry, from which the
discharges on an individual basis are small but the cumulative effect
is far more damaging than large accidental oil spills.
Amant (1) states that ecological disturbances from normal pet
roleum industry practices may be less obvious, more complex and more
permanent than those from accidental events. It is his thesis that
chronic pollution from oil-bleed water and oil emulsion associated
with drilling mud should be considered an effect associated with normal
petroleum industry activities. Even in well managed production areas,
light to moderate oil slicks are common due to bleed water release
and equipment malfunctions. The long range effects of this type of
pollution are unknown. However, small localized biological deserts
are common around tank batteries, separators, and similar facilities
where there is a continuous release of oil and bleed water.
Recent developments in the field of oil separation technology
have, to a large extent, been a result of an extensive research effort
4
whose objective was to develop new methods and materials to aid in
the cleanup of oil spills as well as to prevent the discharge of
polluted waste and bilge water from ships.
5
Oil removal methods are normally classified in the categories
of either physical, chemical, or biological. The last two methods
are the least employed and will be discussed first in the paragraphs
that follow.
Dispersing agents for oil slicks are the most important chemical
method. However, this technique is controversial, due to the fact
that tests in bioassay tanks have indicated an increase in toxicity
levels because dispersing the oil exposes some of the organisms to
higher concentrations. Also, dispersion leaves the oil, in the
environment, and the ultimate fate of chemically dispersed oil and
its effect are yet to be evaluated (8). For these reasons, chemical
dispersants have frequently been employed as a last resort on the
oil slicks near platforms and the shore. They are used only after
permission has been obtained from the appropriate public agency (5).
One other form of chemical treatment is the addition of compounds
to create a gel which minimizes the loss of crude oil from the tanker.
The expense involved in this technique is high, amounting to almost
$4.50 per barrel of crude oil treated. For this reason it has not
been widely accepted within the industry.
Certain bacteria are reported to be responsible for preventing
the accumulation of oil on the earth's surface (12). These microbes
6
are present in areas where natural seepages of oil are present.
Research is presently being conducted to commercially produce such
bacteria on a large scale (8). The use of biological methods for
some time to come will probably be limited to the final polishing
step needed to eliminate traces after the bulk of the oil has been
removed by other methods.
The physical methods employed usually involve either skimming
or a sorbent to remove the oil. Johnson, et !l· (6) classified the
physical methods according to the following categories:
1. floating sorbent +mechanical harvesting;
2. sorbent attached to revolving belts or drums;
3. gelling agent+ mechanical harvesting;
4. mechanical skimming
a) suction pumping + separation,
b) revolving metal drums.
Sorbent materials are used to clean up oil by spreading the
sorbent on the oil surface. This is followed by mixing with oil
and collection of the resulting oil soaked medium. Straw, polyure
thane foams and other sorbents have been employed (2). Recent
studies have shown cotton fibers to have superior sorbent character
istics (6). One of the problems associated with the use of sorbents
is their harvesting and ultimate disposal. In addition, windy condi
tions tend to make the application and retrieval operations difficult
7
To overcome these difficulties, systems have been developed in
which the sorbent becomes part of a revolving belt or drum. This has
been one of the most promising and one of the most widely investigated
techniques. The usual form of the sorbent is an endless belt passing
through a pair of squeeze rollers. Oxenham (13) studied the performance
characteristics of an olephilic belt oil scrubber using a system in
which the belt was drawn over the water's surface across the area of
the oil slick passed through a set of wringers to remove the sorbed oil
and then returned to the water. Oxenham concluded that the rate of
oil absorption by an oleophilic belt increases with the specific sur
face and permeability of the belt material, increasing slick depth,
decreasing oil viscosity, and decreasing interfacial tension between •
oil and belt material. The maximum oil recovery rate is limited by
the rate at which oil may be transferred to the surface.
Milz (11) in his evaluation of oil spill control equipment stated
that generally high oil recovery rates could be achieved with an ab
sorbent surface-skimmers when the device included both drums and
belts. Manjrekar (10) carried out a series of laboratory experiments
to determine an effective belt medium. He found that polyamide and
woolen yarn in the form of tufted carpets picked up the maximum amount
of oil but were commercially not feasible because of their high cost.
Cotton and polypropylene carpet were equally effective. Both of
the carpet materials could be recycled for a long time without
effecting oil pickup. He suggested oleophilizing cotton belts to
reduce the amount of water pickup.
8
Duffy (4) studied cotton belts having a flow-through support ~ system. Instead of the belt being drawn over the surface of the oily
water, the water passed through the belt which acted as both a filter
and a coalescer to remove the oil from the water. An effective flow
through belt system could remove emulsions as well as surface oil.
Duffy worked with cotton belts since they exhibited desirable proper
ties such as oleophilic and hydrophobic qualities, durability, re
silience, flexibility, high strength and low cost. He concluded that
a cotton belt performed satisfactorily as a filter and a coalescer
for separating oil from water and that the textile structure effects
belt performance. Duffy also found that belt efficiency decreased
with use as a result of some form of aging which was not readily
identified.
A similar separation device involved a revolving metal drum in
which the basic mechanism was one of oil adhesion to the metal sur-
face (7). The oil was continuously removed from the rotating drum
by an arrangement of scrapers. The recovery rate depended upon the
viscosity of oil, drum speed and drum diameter.
Johnson, et !1· (6) evaluated the sorption properties of various
unstructured fibers. They related the capacity of the unstructured
fibers to remove crude oil from seawater, to the chemical composition
and to the surface properties of the fibers, as well as the concen
tration, specific gravity and temperature of the crude oil. The study
which was concerned with both natural and man-made fibers, showed
cotton to have superior sorptive capacity compared to the other
fibers. This substantiated Manjrekar's (10} work which had shown
cotton carpets to be a satisfactory belt material.
9
Yu and Ventriglo (15} conducted a state-of-the-art review rela
tive to shipboard oil pollution control systems for ballast and bilge
water. They concluded that no single system was available which could
be successful employed. Yu (16} summarized the conclusions from their
joint study by stating that
.. Separation techniques such as evaporation, distillation, crystallization or freezing are not desirable because of the need for heavy equipment and large supplies of heat or electrical power."
Separation methods using hydrocyclones, chromatography, sound waves,
as well as electric/magnetic and biological techniques were also not
judged to be suitable.
Centrifuging was not considered to be economical since most of
the material centrifuged has to be discarded overboard. Coalescing/
filtering techniques required selective adsorbents for different
materials to be separated. Materials containing surfactants, such
as Navy standard fuel oil have been found to render the presently
known adsorbents ineffective as separating media, after a short period
of time.
Chemical treatment was not the preferred method because it re
quired skilled operators to administer the chemicals. It can also
10
introduce another pollutant and it may require special materials of
construction. A limited use of chemicals to assist in breaking tight~
water oil emulsions is, however, probably not objectional. ) Settling due to gravity effects was the preferred method because)
::0i::0:o:::t~::d~~:9c~::9:n:0~::::i::t:~ll:::h::::r:e::1::: 1 :a:r::_ ~ ably be suitable for handling the smaller volumes of bilge water at
low flow rates.
In a report for the Water Quality Office of the Environmental
Protection Agency, Hydroscience Incorporated (3) reported that typi
cal ordinances require removal of any free or floating oil and the
amount of hexane soluble oil must be less than 50 mg/1. Hydroscience,
Incorporated concluded that oil in wastewater going to a biological
treatment facility should be less than 75 mg/1 and preferably below
50 mg/1.
There is a very meager amount of published literature on the
oil-in-water coalescing properties of any type of media. To gain an
insight into the phenomena of coalescence and the effect of flow rate
and temperature on the operational life of the coalescing media,
research is needed. In previous research cotton fabrics have demon
strated their ability to separate oil from certain streams and
further research is needed to study their behavior as coalescers in
a static device.
CHAPTER III
EXPERIMENTAL APPARATUS, OPERATING PROCEDURE
AND ANALYTICAL TECHNIQUE
Two different prototypes of the static oil-water separator have
been constructed and tested to date.
In all cases, the first medium in the sequence of filters/
coalescer elements was made of burlap. This material was chosen
because its large pore size which would act as a screen to filter out
any coarse particles in the stream, and thereby prevent plugging of
the filter/coalescer elements in the other compartments.
The burlap was followed downstream by three or four cotton terry
towel filter/coalescer elements. The terry towel was sewn in the form
of a glove to fit a metal frame which occupied the entire cross-section
of the device.
The filter/coalescer elements were housed in a rectangular channel.
Three sides of this channel were made of 16 guage steel plates and the
other side was constructed of plexiglass. The ends and sides of the
steel channel were reinforced with angle iron to provide support for
the side made of plastic. The plexiglass side was held in place by
clamps and gum rubber was used as a gasket material between the plexi
glass cover and the steel.
The wood prototype was named Ben's Babe while the separator was
christened MK II. The steel separator was divided into four compart
ments with entry and exit sections as shown in Figure 1. The wooden
11
(3)
(3)
(3)
~ "
(2)~
~ r
(l)
_,.
_A
4
;a. ( 2
) ..
• ~
...
, .....
. r
? _t
.. ~
~
4 3
2 E
~~
, ~~
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4,.
.. ~
( 1 )
( 1 )
( 1 )
Side
View
*2
-tM~,...._. _
_ _
11 ---
... t-
41
4r-
----
11
-··~
11
Top
View
Fi
gure
1
-S
epar
ator
(2)
~
(3)
~ r
•A
4
.. ~
~ -'to 1
811
1 In
let
~ "l'
Inle
t ~
Sam
plin
g ·~
V
alve
( 1
)
{1)
Oil
and
Air
Ble
ed
Val
ves
(2)
Sam
plin
g V
alve
s (3
) M
anom
eter
Con
nect
ions
~r
11
__,
N
13
prototype had three compartments but approximately the same dimen
sions as MK II. The dimensions of MK II are tabulated in Table I.
Length Width Depth
TABLE I
DIMENSIONS OF MK II
Length of last compartment Length of entry section Length of exit section Volume of separator
48 in. 7 7/8 in. 8 in.
11 in. 2 in. 2 in. 1.75 ft3
During runs 4 through 11, there were no means of sampling the
water nor of measuring the pressure in each compartment. To sample
the water in each compartment, measure the pressure, and at the same
time remove the oil, valves were provided at the top and bottom of
each compartment (Figure 1). In addition, the pressure drop across
the separator was measured using a pressure gauge at the inlet to the
separator while the exit was open to the atmosphere. A flow schema
tic of the system is shown in Figure 2 and Figure 3.
The cotton filter/coalescer elements were supported by a steel
frame. Two types of frames were employed in this study. The first
(1)
Oil
and
Air
Ble
ed
Val
ves
{2)
Sam
plin
g V
alve
s
Syph
on
Bre
aker
Eff
luen
t
( 1 )
(2)
( 1)
( 1 )
(2)
(2)
( 1 )
(2)
Inle
t Fl
ow
Con
trol
V
alve
Rot
amet
er
(2)
Figu
re
2 -
Oil-
Wat
er F
eed
Syst
em
Stea
m
Wat
er
Val
ve
t--f)()-
Air
18
ps
ig
Oil
Con
trol
V
alve
__. ~
(1)
Oil
and
Air
Ble
ed
Val
ves
(2)
Sam
plin
g V
alve
s (3
) M
anom
eter
Con
nect
ions
(3)
(3)
(3)
(3)
Syph
on (
l )-M
-(1
)-w
-(1
) -*
""1
1-0
0-1
B
reak
er
Eff
luen
t
(2)
(2)
(2)
(2)
Flow
Con
trol
Val
ve
Oil
Shu
toff
V
alve
Pum
p R
otam
eter
Figu
re
3 -
Mod
ified
Wat
er H
eatin
g Sy
stem
Stea
m Stea
m
Oil
Con
trol
Val
ve
Wat
er Se
cond
Fl
oor
Cher
n. E
ngr.
Bld
g.
~
Oil
Oil
Bas
emen
t ~
c.n
16
type was made of l/2 11 steel and had an open area of 6 7/8 11 x 6 15/16 11,
which is a cross-sectional area of 0.3312 ft2• This type of frame
was replaced on thP theory that free oil may be wicking across the
top of the filter/coalescer elements and also saturating the terry
towel ..
To stop any possibility of oil wicking or saturating the terry
towel elements, the frames were modified by blocking the upper two
inches with metal. This reduced the area available for flow to
4 11/16 11 x 6 7/8", which is a cross-sectional area of 0.223 ft2.
Leaks around the filter/coalescer plates were prevented by sealing
with silicone seal. Even though significant precautions were taken,
occasional leaks were observed during some runs.
The separator was mounted on a steel frame 10 1/2 11 in height to
allow lines to be connected to the bottom for removal of water samples.
The entire assembly was placed on a table mounted on castors, which
allowed one separator to be easily and quickly replaced by another.
The separator was connected to the oil-water system by a 3/4 11 flexible
rubber hose.
Oil-water Feed System
The water was pumped from a stainless steel holding tank for runs
4 to 15. Figure 2 is a schematic diagram of the flow system. For runs
16 to 20 an 800 gallon galvanized iron tank on the second floor of the
Chemical Engineering building was used as a feed tank with the experi
ments being conducted in the basement as shown in Figure 3. A
centrifugal pump with a 2" suction line and 1 1/211 discharge line
was employed to provide the needed pressure drop. The flow rate
was controlled by a 1 1/411 globe valve on the discharge line from
the pump. The line between the globe valve and the separator was
a 3/411 black rubber hose.
17
The oil was stored in two 7 gallon steel tanks under a pressure
of 16-18 psig. The two tanks were connected in parallel to each
other and the oil was fed through l/411 copper tubing to a point
immediately in front of the pump suction. The passage of oil and
water through the pump results in a fine emulsion. The oil flow
rate was monitored by a rotameter and controlled by a 1/411 needle
valve.
Water-heating System
When water was pumped from the stainless steel tank, it was
heated by direct condensation of steam. This was the case for all
runs prior to 16. For run 16 and those that followed, the water
was heated by a double pipe heat exchanger as shown in Figure 3.
Analytical Procedure for Oil in Water
For consistency with previous work done at Texas Tech the pro
cedure adopted for determination of oil in water was the same as
adopted by Duffy (11) except for a change in the cooling method
associated with the oil residue and is reproduced from his thesis.
18
PROCEDURE
Extraction was peformed in a 2-liter separatory funnel using
petroleum ether. Prior to extraction, 5 ml of concentrated H2so4 were added to the sample to break any emulsion present. The empty
sample bottle was rinsed with 50 ml of petroleum ether and the
washings added to the separatory funnel. After two minutes of
vigorous shaking, the funnel contents were allowed to separate. The
aqueous portion was withdrawn into the sample bottle and the extract
was placed in a graduated cylinder. To assure complete oil recovery
the aqueous portion was extracted a second time.
After the second extraction, the aqueous phase was discarded
and the ether extract was added to the graduated cylinder. The
separatory funnel was rinsed with 20 ml ether which was added to the
extract. The graduated cylinder was shaken several times to mix the
contents. Noting the extract volume, 50 ml were placed in a tared
platinum evaporating dish. The dish was set on a water bath until
the ether evaporated leaving only an oil residue. It was cooled
under vacuum for ten minutes to remove any traces of ether. Knowing
the weight of the oil residue, the sample oil concentration was
calculated using the following formula:
mg oil {PPM) 1 sample
= g oil residue ml extract 1069m~ ml 50 ml extract ml sample
19
Residence Time Measurement
The residence time of fluid within the filter/coalescer was
measured by injecting a red dye into the rubber hose and noting the
time required for the dye to move from the inlet to the outlet of
the separator by visually observing its passage through the plexi
glass section.
Per Cent Removed by Gravity
In order to compare the results obtained from coalescence with
those that could be obtained during a comparable time period in a
gravity separator, a sample was withdrawn from the inlet sampling
port into two liter separatory funnels in which the depth of the sample
was approximately 8", the same as the height of the fluid in the
separator. This sample was allowed to stand for the same period of
time as the experimentally measured residence time and a sample of
the water phase withdrawn from the separatory funnel. There is a
difference in head for portions of the sample in the funnel; however,
difference between the amount of oil in the inlet and the amount of
oil measured in the above sample was attributed to the amount of oil
which could have been removed by simple gravity separation in a
somewhat comparable time period.
Operating Procedure
Tap water was run through the separator and was slowly heated
to the desired temperature. Once the flow rate had stabilized at
20
some predetermined valve the oil feed was started. In the beginning
of the run, the temperature, flow rate total ~P and individual pres
sure in each compartment were recorded. The first set of inlet {IN)
and effluent {EFF) samples were taken one hour after the run was
initiated. The second set of similar samples, as well as compartment
samples, were taken two hours after the run was initiated and subse
quent similar samples were taken after every two hours. Temperature,
water flow rate, pressures, and the oil flow rate were recorded when
ever samples were taken. Residence time measurements and gravity
samples were taken at random. The flow rate was calculated from a
determination of the time required to collect four liters of the
effluent.
Influent and effluent samples were collected in quart jars,
while the compartment samples were collected in pint jars, since
withdrawing a quart of sample simultaneously from each compartment
would have upset the system.
CHAPTER IV
DISCUSSION OF RESULTS
A wooden prototype was initially constructed to test the con
ceptual feasibility of the device. It was planned to develop the
design for a metal prototype on the basis of the initial runs.
In the tests described below, runs 2, 3 and 4 were made using the
wooden prototype, while runs 5 through 20 were conducted using the
metal prototype. The wooden prototype had three compartments while
the metal protytype had four compartments. The first filter/coalescer
element in all cases was burlap, followed by terry towel filter/
coalescer elements.
As shown in Table II, runs 2 and 3 were made at room temperature
and at approximately the same flow rate. Oils of different viscosi
ties were employed with SAE 30-W oil used for run 2 and OE-50 for
run 3. These were preliminary trials and the removal efficiences,
pressure drop across the device, and flow rate indicated that further
investigation was warranted. Visual observation made during runs 2
and 3 indicated that the maximum amount of oil buildup occurred in
the first compartment (Cl) and the least amount in the last compar
ment (C3). Visually it appeared that the oil buildup occurred
linearly across the separator. Figure 4, which is the plot of the
system efficiency (%oil removal) versus time, indicated that the
decrease of efficiency with time was marked for run 2 and less
marked for run 3. The difference was attributed to the difference
21
Run
No.
:
2 W
ater
Typ
e:
Cit
y 2
Flow
Are
a =
0.4
0 ft
N
o.
of
Sta
ges
= 3
O
il Ty
pe =
SAE
=30W
T
empe
ratu
re =
70°
F
TABL
E II
INIT
IAL
FEA
SIBI
LITY
TES
T
No.
of F
ilte
r/C
oale
scer
s:
Bur
lap=
1;
Ter
ry T
owe1
=3
Hou
rs
into
Run
1
2 3
4
Flow
rat
e gp
m
7.92
6.
67
8.80
8.
93
Lin
ear
velo
city
ft
/min
2.
609
2.19
7 2.
899
2.94
0 In
flue
nt o
il
cone
. pp
m
1364
16
06
1142
12
09
% O
il re
mov
al
93.6
89
.1
83.0
75
.2
~p A
cros
s 2
sepa
rato
r lb
/in
2.
05
1 .8
2.2
2.25
5 6
8.93
8.
93
2.94
0 2.
940
1314
15
89
73.5
74
.8
2.25
2.
25
7 10.5
6
3.47
9
1461
45
.7
2.48
Ave
rage
8.67
2.85
5
1383
75
.7
2.18
N
N
TABL
E II
(c
onti
nued
) ..
....
.
Run
No.
: 3
Wat
er T
ype:
C
ity
2 Fl
ow A
rea
= 0
.40
ft
No.
of
Sta
ges
= 3
O
il Ty
pe =
OE-
50
Tem
pera
ture
= 70
°F
No.
of
Fil
ter/
Coa
lesc
ers:
B
urla
p=l;
Ter
ry,T
owel
=3
Hou
rs
into
Run
1
2 3
4
Flow
rat
e gp
m
7.92
7.
92
8.34
9.
05
Lin
ear
velo
city
ft
/min
2.
609
2.60
9 2.
746
2.98
2 In
flue
nt o
il c
one.
pp
m
428.
9 41
1.4
399.
1 41
0 %
Oil
rem
oval
88
.2
88.8
90
.2
89.7
~p A
cros
s 2
sepa
rato
r 1b
/in
1.4
1.4
1.45
1.
50
5 6
9.32
8.
80
3.07
0 2.
899
339.
6 37
8.6
87.6
89
.7
1 .4
1 .4
7 8.34
2.74
6
670.
6 85
.5
1.4
Ave
rage
8.52
2.80
8
434 88
.5
1 .42
N w
100 80
-tO >
0 60
E
Q
) c:
: - -0 ~
40
20
--P
-
-x--=-
-~---
~-_ -
_ L
-_
_ J.
(_
Run
3 --
---
--~
--/\
GJ--
---
---
----..
Bun_
? 0
Q
0 R
un
2 X
R
un
3
_X
_
OE-
50
Oi 1
X
----
0 S
A£-
30 O
iJ
---
----
----
---
0
~--------------~------~------~------~------------------------~
0 1
2 3
4 5
6 7
8
Hou
rs
into
Run
Figu
re
4 -
Woo
den
Pro
toty
pe
3 C
ompa
rtmen
ts
N ~
25
in oil viscosities. The dashed lines on all of the figures are shown
to indicate trends and were not the result of any mathematical model.
This behavior, with respect to time, was expected and indicated that
the system would be ineffective after a length of time. That is,
the breakthrough point of the system would have been reached in a
relatively short time.
In view of this initial work, an all metal model was constructed.
The major problem in the operation of the new model was the persistent}
leaks around the filter/coalescer support system. Results for runs
6 and 7 during which persistent leaking occurred are shown in Table III.
OE-10 is a light oil and produced a stable emulsion which did not
readily separate on standing. Runs 6 and 7 were made under identical
conditions of flow rate, temperature, and inlet oil concentration.
Figure 5, which is a plot of percent oil removal versus time, showed
a sharp decrease in the system efficiency with time. This plot must
be viewed, keeping in consideration the fact that runs 2 and 3 had
three compartments while runs 6 and 7 had four compartments. The
difference between the effluent oil concentration of the two runs
can be attributed to the presence of leaks, visually observed during
the run, around the last filter/coalescer element. Oil buildup did
not follow the linear pattern of runs 2 and 3. Oil buildup occurred
in the first and last compartment (Cl and C4) with very little oil
in the second and third compartments. This behavior could have been
due to leaks around the filter/coalescer elements in compartments
Run
No.
: 6
Wat
er T
ype:
C
ity
2 Fl
ow A
rea
= 0
.33
ft
No.
of S
tage
s =
4
Oil
Typ
e= O
E-10
T
empe
ratu
re =
70°
F
TABL
E II
I
TEST
S W
ITH
LIGH
T OI
L US
ING
Mki
i
No.
of F
ilte
r/C
oale
scer
s:
Bur
lap=
l; T
erry
Tow
el=4
Hou
rs
into
Run
1
2 3
4 5
Flow
rat
e gp
m
9.90
9.
32
9.05
8.
93
8.80
L
inea
r ve
loci
ty
ft/m
in
3.97
5 3.
741
3.63
5 3.
583
3.53
4 In
flue
nt o
il c
one.
pp
m
1012
.0
1041
.0
1036
.0
1092
.0
1072
.0
% O
il re
mov
al
79
73
16
37
31
6p A
cros
s 2
sepa
rato
r lb
/in
2.
1 2.
1 2.
1 2.
3 2.
3
6 7
--
--
--
--
--
Ave
rage
9.2
3.6
1050
47
.2
2.18
N
0'\
TABL
E II
I (c
onti
nued
) ..
....
.
Run
No.
: 7
Wat
er T
ype:
C
ity
2 Fl
ow A
rea
= 0
.33
ft
No.
of S
tage
s =
4
Oil
Typ
e=
)E-1
0 T
empe
ratu
re =
70°
F No
. F
ilte
r/C
oa1e
scer
s:
Bur
lap=
l; T
erry
Tow
el=4
Hou
rs
into
Run
1
2 3
Flow
rat
e gp
m
8.34
9.
60
9.32
L
inea
r ve
loci
ty
ft/m
in
3.34
3.
85
3.74
In
flue
nt o
il c
one.
pp
m
1039
10
19
1046
E
fflu
ent
oil
con
. pp
m
1191
14
9 28
8 %
Oil
rem
oval
88
.5
85.3
72
.4
~p A
cros
s 2
sepa
rato
r lb
/in
1.
8 2.
0 2.
1
4 5
6
9.18
-
-3.
68
--
1120
-
-63
9 -
-43
-
-2.
2 -
-
7 - - - - - -
Ave
rage
9.11
3.65
1056
298 72
.3
2.02
N ........
,..... "' > 0 E
Q)
0::
,....
.
100 80
60
1-
0 40
~
20 0
&
0
X Ru
n 7
Oi 1
OE-
1 0
es>Ru
n 6
Oil
OE-
10
..... '
""'-X
'
.....
' ',
.....
4>'
', '
...... ..
... ...
X
. ,
0 '...
......
. X
'
' ..
1 2
......
..... .....
....
... .....
...
" ....
........
..
" ....
........
..
' ',
""'
........
......
.........
.....,
..........
',
"'
X
. .....
.....
0 '
0 3.
4 H
ours
in
to R
un
.........
..........
. 0 .....
.........
5 6
Figu
re
5 -
Eff
ects
of
Leak
s in
Sys
tem
MK
II-4
Com
partm
ents
N
(X)
29
two and three or to the need for more filter/coalescer elements in
order to break the emulsion obtained using OE-10 oil.
Another observation at this point in the experimental program
was the presence of coalesced oil in the effluent. This was thought
to be due to one or a combination of several possible causes: A
leak around the last filter/coalescer element; the wicking of oil
across the filter/coalescer elements due to the capillary action of
the fibers; or to the saturation of the filter/coalescer elements
by the oil and the subsequent breakthrough of the oil in the region
where the oil was in contact with filter/coalescer elements.
The use of silicone glue worked well in reducing leaks. Modifi
cation of the filter/coalescer supports by blocking the top with a
steel plate eliminated any possibility of oil wicking or saturating
the filter/coalescer elements. This reduced the flow area from
0.33 ft2 to 0.22 ft2.
After these modifications had been made, the system efficiency
increased dramatically, as shown in Table IV and Figure 6 for run 11,
compared to runs 6 and 7. The blockage of the top quarter of the
frames and occasionally draining the oil increased the life of the
filter/coalescer elements and appeared to eliminate the problem of
breakthrough. However, due to the reduction of the flow area a
higher pressure drop was needed to maintain the flow rate of previous
runs.
Run
No.
: 11
W
ater
Typ
e:
City
2
Flow
Are
a =
0.2
2 ft
No
. of
Sta
ges
= 4
O
il Ty
pe =
OE-
10
Tem
pera
ture
= 7
0°F
TABL
E IV
EFFE
CT O
F M
ODIF
YING
FI
LTER
/COA
LESC
ER S
UPPO
RTS
No.
of F
ilte
r/C
oale
scer
s:
Bur
lap=
l; T
erry
Tow
el=4
Hou
rs
into
Run
1
2 3
4 5
Flow
rat
e gp
m
12.1
8 9.
18
9.05
9.
05
-L
inea
r ve
loci
ty
ft/m
in
7.60
5.
50
5.42
5.
42
-In
flue
nt o
il c
one.
pp
m
646
1037
73
1 86
4 -
Eff
luen
t oi
l co
ne.
ppm
68
115.
8 10
1 10
0 -
~P A
cros
s 2
2.6
2.3
2.4
2.4
sepa
rato
r 1 b
/in
-
6 7
Ave
rage
--
9.99
--
5.98
5
--
819.
5
--
96.2
--
2.42
w
0
,_.
ItS
>
0 E
Q)
0::
,_. ·-10
0 80
0 60
1-
~~
40
0
0 Ru
n 11
0 i
1 O
E-1 0
X
Ru
n 15
Oi
1 O
E-1
0
-*-
--x-
---
-x-
--
-x-
--
-x
---
-X---
_x_
---
--;~
--
-<il\-
------
--~-
----
----
----
----
---.
0--
0
I I
I _
.I.
I
1 2
3 4
5 6
7 8
Hou
rs
into
Run
Figu
re
6 -
Eff
ect
of M
odify
ing
Fi1
ter/
Coa
1esc
er S
uppo
rts
w
__,
32
The system exhibited good removal of oil at room temperature
but no prediction could be made of its performance at higher water
temperature. Run 13 was made to determine if there was a break
through time for the system, as well as, to determine the effect of
high temperature. The results for the first three hours of the run
are summarized in Table IV. The average temperature was 134°F but
temperatures higher than 170°F did occur during the run due to poor
control. Difficulty was experienced in maintaining a steady flow rate
of 1.5 gpm, which was much lower than the previous lower temperature
rates. The pressure drop across the separator increased rapidly
from its initial high value as compared to previous runs. The flow
rate dropped significantly from 1.5 gpm at the start of the run to
0.8 gpm three hours into the run and 20 hours into the run it was
0.2 gpm. No explanation is available at this stage for the strange
behavior observed in run 13. It could have been due to a tempera
ture effect or it may have been rust initially present in the lines
which blocked the filter/coalescer elements.
Operating procedure change was carried out at this point.
Before initiating a test, all lines were drained. To find the
limiting temperature, a series of tests were initiated. The results
for run 15, which was the first in the series, are shown in Table VI.
The average temperature during the run was 101°F. The plot of ef
ficiency versus hours into the run is the horizontal line on Figure 6
Run
No.
: 13
W
ater
Typ
e:
City
2
Flow
Are
a =
0
. 22
ft
No.
of S
tage
s =
4
0 i 1
Typ
e =
0 E
-1 0
TABL
E V
EFFE
CT O
F TE
MPE
RATU
RE
No.
of F
ilte
r/C
oale
scer
s:
Bur
lap=
l; T
erry
Tow
e1=4
Hou
rs
into
Run
1
2 3
4
Flow
rat
e gp
m
1 .44
1.
20
-0.
834
Lin
ear
velo
city
ft
/min
0.
867
0.75
7 -
0.50
T
empe
ratu
re °
F 15
0 14
8 -
152
% R
emov
al
by g
ravi
ty
69
-54
.5
Res
iden
ce t
ime
2 m
in
-2
min
15
sec
38
sec
C
ompa
rtmen
t oi
l co
ne.
ppm
c,
17
5 17
9
c2
156
162
--
c3
155
140
c4
68
62
5 6
7 A
vera
ge
--
--
w
w
TABL
E V
(co
ntin
ued)
..
..••
•
Hou
rs
into
Run
1
Infl
uent
oil
co
ne.
ppm
12
14
Eff
luen
t oi
l co
ne.
ppm
50
%
Oil
rem
oval
95
6p
A
cros
s se
para
tor
lb/i
n2
8
2 3
1461
.3
-
35.5
-
97.5
-
8.6
-
4
7204
33.9
99
8.8
5 6
7 A
vera
ge w
~
35
which shows no signs of breakthrough. In addition, an extremely
low amount of oil was measured in the effluent.
During run 15, the concentration of oil in the water phase in
each compartment was measured. The concentration in each compart
ment showed no significant change as the run progressed.
The maximum removal occurred in the first compartment. This
could be expected since any free oil together with the coalesced
larger droplet would float to the top allowing the emulsified oil
to pass into the second compartment. In the subsequent compartments
the terry towel filter/coalescers attempt to break the emulsion.
The percent removal versus from compartment to compartment, and is
not linear. In one run the observed removals were as follows:
Average PPM % Removal Between Oil Stages
Inlet 1270 cl 303 76 c2 106 65 c3 76 28 c 37.1 51 Effluent 29 21
The residence time in the separator, as defined in the previous
chapter was measured and used in estimating the per cent removal by
gravity, which, in this case, was about 60%. The per cent removal
by gravity in actual practice will be lower than that measured by the
procedure outlined in the previous chapter. The reason for this
Run
No.
: 15
W
ater
Typ
e:
Cit
y 2
Flow
Are
a =
0.2
2 ft
N
o.
of S
tage
s =
4
Oil
Typ
e= O
E-10
TABL
E VI
BREA
KTHR
OUGH
POI
NT T
EST
No.
o
f F
ilte
r/C
oa1e
scer
s:
Bur
lap=
l; T
erry
Tow
e1=4
Hou
rs
into
Run
1
2 3
4
Flow
rat
e gp
m
2.34
2.
39
2.18
2.
48
Lin
ear
velo
city
ft
/min
1.
40
1.43
1.
31
1. 4
9 T
empe
ratu
re
oF
101
101
101
100
% R
emov
al
by g
ravi
ty
--
--
Res
iden
ce t
ime
--
--
Com
partm
ent
oil
co
ne.
ppm
30
48.5
* c1
34
3.5
339.
5 27
7.3
c2
108.
7 10
2 12
5 12
7
c3
87.1
83
86
.5
79.6
c4
38.5
41
35
38
.1
* D
eem
ed
to b
e an
o
utl
ier
not
incl
uded
in
th
e av
erag
e.
5 6
7 8
Ave
rage
2.43
2.
48
2.48
2.
18
2.37
1. 46
1.
49
1. 4
9 1 .
31
1. 4
2 10
0 10
0 10
0 11
0 10
1 -
--
60
--
-1
min
45
sec
295.
5 29
5.9
305.
1 26
5.7
303.
2
105
105
104.
1 77
10
6 76
72
.8
71.3
53
76
34
34
.7
38.9
37
37
. 1
w
0"1
TABL
E VI
(c
onti
nued
) ..
....
.
Hou
rs
into
Run
1
2 3
4
Infl
uent
oil
co
ne.
ppm
11
43.8
11
52.4
11
15
1082
.4
Eff
luen
t o
il
cone
. pp
m
22.8
26
.35
30.2
27
.3
% O
il re
mov
al
98
97.7
97
.2
97.4
~p A
cros
s se
para
tor
lb/i
n2
1. 1
2 1.
37
1. 3
7 1.
62
5 6
7
1046
92
0 12
96.8
26
25
27. 1
97
.5
97.5
97
.9
1. 6
2 1.
75
1.75
8
1261
.8
48
96 2
Ave
rage
1270
29
97.3
1. 5
w
........
38
being, the time lag required to fill the separatory funnel to the
same height as the water in the oil-water separator, plus the time
taken to drain the sample from the funnel. The shape of the funnel
will also play a part in the amount of oil separating.
Next a marathon run was planned to determine the breakthrough'\
point. Run 17, the results for which are shown in Table VI, lasted \
50 hours; had an average flow rate of 2.7 gpm, an average tempera-.
ture of 94°F, and base~ on the manometer reading from the first,
an average ~p of 3.03 psig. In order to minimize wicking problems,
oil was periodically drained from the compartments. The system ef
ficiency decreased with time at a very slow rate as shown in Figure
7. At the end of 50 hours, the efficiency was 86% with no indications
of a breakthrough. The highest efficiency during the run was 90% and
the lowest, 79%. The average efficiency during the run was 86%. Oil \
buildup through the device was not linear. The maximum amount of oil
was removed from compartment one followed by compartment four. During
this run an air space developed in compartments one and four. The
air was drained out periodically to keep the oil level from reaching
the terry towel. This phenomenon has also been observed in later
runs and may be due to air leaking into some joint or valve in the
lines. This does indicate that the separator itself was pressure
tight.
The difference between run 17 and the runs preceeding 17 was the
use of a double pipe heat exchanger to heat up the water during run
l
Run
No.
: 17
W
ater
Typ
e:
Cit
y 2
Flow
Are
a =
0.2
2 ft
N
o.
of
Sta
ges
= 4
O
il T
ype=
OE-
10
TABL
E V
II
BREA
KTHR
OUGH
POI
NT T
EST
No.
o
f F
ilte
r/C
oale
scer
s:
Bur
lap=
1; T
erry
Tow
e1=4
Hou
rs
Flow
L
inea
r ~p
from
O
il C
one.
pp
m in
to
Rat
e V
eloc
ity
c, Te
mp.
Ru
n gp
m
ft/m
in
Man
omet
er
OF
Inle
t E
fflu
ent
2 3.
01
1.8
2.86
92
76
7 86
.2
4 2.
75
1.65
2.
90
107
868
30
6 2.
75
1.65
2.
97
101
747
100.
7 8
2.75
1.
65
2.99
10
2 82
4.8
101.
2 10
2.
75
1.65
2.
99
102
982
119
12
2.75
1.
65
3.05
10
2 76
1.7
128.
9 14
2.
75
1.65
3.
05
102
860.
9 12
3.1
16
2.75
1.
65
3.19
10
2 80
0.4
105.
3 18
2.
64
1.68
3.
46
101
747
130
20
2.81
1.
68
3.32
10
1 88
6 13
1 22
2.
75
1. 6
5 3.
40
105
885
123
24
2.75
1.
65
3.44
10
2 81
2.3
120.
2
%
% O
il R
esid
ence
R
emov
al
by
Rem
oval
Ti
me
Gra
vity
88.7
96
.5
86.5
87
.7
87.8
83
85
.6
1 m
in 3
5 se
c 64
.8
86.8
81
.7
1 m
in 4
0 se
c 10
.7
85.2
86
1
min
22
sec
59.8
85
.2
--
w
\0
TABL
E V
II (c
onti
nued
) ..
....
.
Hou
rs
Flow
L
inea
r in
to
Rat
e V
eloc
ity
~p
Tem
p.
Run
gpm
ft
/min
lb
/in
2 O
f
26
2.75
1.
65
3.44
10
2 28
2.
75
1.65
3.
44
102
30
2.64
1.
58
3.44
10
2 32
2.
53
1. 5
2 3.
48
101
34
2.64
1.
58
3.55
10
1 36
2.
64
1. 5
8 3.
57
101
38
2.53
1.
58
3.57
10
1 40
2.
53
1. 52
3.
61
101
42
2.75
1.
52
4.02
10
2 44
2.
75
1. 65
3.
88
98
46
2.75
1.
65
3.9
102
48
2.75
1.
65
4.1
104
50
2.75
1.
65
4.02
10
0 A
vera
ge
2.71
1.
62
3.03
10
1.4
"2. '
F-.
7:
.....
·._. "'
Oil
Con
e.
ppm
Inle
t E
fflu
ent
921.
5 11
9.1
926.
2 14
7.5
880.
3 12
1.5
790
125.
8 99
5.3
135.
4 11
89.7
12
5.9
1747
.2
118.
1 12
60
120.
5 87
7.3
146.
9 82
7.7
172
-12
6 73
9.9
121.
8 85
5.9
117.
8 87
7 11
0.6
% O
il Re
mov
al
87.3
84
86
.1
84
86.3
89
.4
83.2
90
.4
83.9
79
.2
83.5
86
.2
86
Res
iden
ce
Tim
e
1 m
in
40 s
ec
1 m
in
35 s
ec
1 m
in
42 s
ec
1 m
in
34 s
ec
-
%
Rem
oval
by
G
ravi
ty
52.6
54
.4
52.6
49.7
48.5
..t=-
0
TABL
E V
II (c
onti
nued
) ..
....
.
Run
No.
: 18
W
ater
Typ
e:
Cit
y 2
Flow
Are
a =
0.2
2 ft
N
o. of
Sta
ges
= 4
O
il Ty
pe:
OE-
10
No.
of
Fil
ter/
Coa
1esc
ers:
B
urla
p=l;
Ter
ry T
owe1
=4
Hou
rs
into
Run
2
4 6
Flow
rat
e gp
m
2.88
2.
88
2.75
L
inea
r ve
loci
ty
1.72
1.
72
1.65
ft
/min
T
empe
ratu
re °
F 11
0 99
98
R
esid
ence
tim
e 1
min
1
min
1
min
30
sec
30
sec
34
sec
%
Rem
oval
by
gra
vity
47
.5
51.4
48
.6
Infl
uent
oil
con
e.
ppm
64
8.9
605.
8 85
1.7
Eff
luen
t o
il c
one.
pp
m
85.5
10
2.2
143
% O
il re
mov
al
86.8
83
.6
83.2
~p A
cros
s se
para
tor
from
C1
man
omet
er
2.39
2.
57
2.70
lb
/in2
8 A
vera
ge
2.75
2.
8 1.
65
1. 6
8
98
101.
25
-1
min
-
33 s
ec
-49
.1
848.
8 73
8.8
140
117.
6 83
.4
84.2
~
2.99
2.
66
~
42 0 ,....- - ~ I ..., LJJ 0
,....- 0 .,...
I 0
........ ,....-
l c: 0 -~ :::s
0:::
~ G
0 I Q - 00
I M
0
J 'G) _N
I M +J
C/) Q)
0 t-
I ..s::::: en
~ :::s c: 0
~' :::s ~
0::: ..s::::: _\.0 +J
19 N 0 ~
+J tO c: Q) .,... ~
I co
~ C/)
~ :::s ........
b 0
:X: Q) ~
0 :::s
I N en .,...
LL. ®
l 10 _o:::;t
,....-
I Q
1 ~ 00
10 0 1
l I I N 0 '"' 0 0 0 0 co \.0 q-,....-
L~Aowa~ L~O %
43
17 as shown in Figure 3 and the condensation of steam in the tank as
shown in Figure 2 in case of runs preceeding 17.
The average residence time was 1 minute 34 seconds and the
average removal by gravity was 48.5%. This meant that at least 37.5%
of the oil was removed by the introduction of the filter/coaleascer
elements and this percentage of oil would be very difficult to remove
by simple gravity separation because it probably represents the very
finely dispersed emulsification phase.
The results of run 18 are shown in Table VII. The duration of
this run was six hours and the data indicate that at least over this
time period the performance of the system is reproducible with respect
to run 17. Figure 8 shows the change in the system efficiency as the
run progressed.
Runs 19 and 20 were made at an average temperature of 148 and
158°F, respectively, and the results are shown in Table VIII. The
higher temperatures did not show any significant effect on the per
cent removal as compared to previous runs. However, a slightly
higher driving force was required to maintain the same flow rate
compared to tests at 100°F. This could have been due to the swelling
of the cotton fibers or the change in the viscosity of the oil-water
emulsion shown in Figure 8. The decrease of removal efficiency with
time was slow.
Table IX summarizes the average values for the flow rate, ~p,
operating temperature, inlet oil concentration, outlet oil concentration
Run
No.
: 19
W
ater
Typ
e:
Cit
y 2
Flow
Are
a =
0.2
2 ft
N
o.
of S
tage
s =
4
Oil
Type
= O
E 10
TABL
E V
III
EFFE
CT O
F TE
MPE
RATU
RE
No.
of
Fil
ter/
Coa
lesc
ers:
B
urla
p=l;
Ter
ry T
owel
=4
Hou
rs
into
Run
1
2 4
Flow
rat
e gp
m
2.53
2.
88
2.64
L
inea
r ve
loci
ty
ft/m
in
1. 52
1.
72
1. 5
8 T
empe
ratu
re °
F 15
8 14
4 14
5 R
esid
ence
tim
e -
--
% R
emov
al
by g
ravi
ty
--
-In
flue
nt o
il c
one.
pp
m
955
822
770.
6 E
fflu
net
oil
con
e.
ppm
71
.7
77
280.
9 %
Oil
rem
oval
92
.4
90
63
~P A
cros
s se
para
tor
from
c1
man
omet
er
lb/i
n2
3.19
3.
77
2.50
6 8
Ave
rage
2.75
2.
64
2.68
1.65
1.
58
1. 61
14
3 14
3 14
8 1
min
32
sec
79
998.
5 11
79.1
96
5.1
112
89.9
12
5.3
88.4
92
.7
85.3
~
~
2.50
2.
70
2.46
Run
No.
: 20
W
ater
Typ
e:
Cit
y 2
Flow
Are
a =
0.2
2 ft
No
. of
Sta
ges
= 4
O
il T
ype=
OE-
10
TABL
E V
III
EFFE
CT O
F TE
MPE
RATU
RE
No.
of
Fi1
ter/
Coa
1esc
ers:
B
urla
p=1;
Ter
ry T
owe1
=4
Hou
rs
into
Run
1
2 5
6 8
Flow
rat
e gp
m
2.64
2.
53
2.88
2.
75
2.83
L
inea
r ve
loci
ty
ft/m
in
1. 5
8 1.
52
1. 7
2 1.
65
1. 6
5 T
empe
ratu
re
166
170
163
159
164
% R
emov
al
by g
ravi
ty
-74
.2
--
72.7
4 R
esid
ence
tim
e -
1 m
in
--
1 m
in
11
sec
34 s
ec
Infl
uent
oil
co
ne.
ppm
60
3.7
1409
.6
1397
.4
1804
.3
1018
.4
% O
il re
mov
al
93.1
96
.6
92.2
93
.7
92
~P A
cros
s 2
sepa
rato
r lb
/in
3.
92
from
c1
man
omet
er
3.73
4.
39
4.66
4.
79
10
12
Ave
rage
2.83
2.
81
2.74
1. 6
9 1.
68
159
159
73.4
1
min
22
sec
957
1136
.5
1206
90
.2
92.9
92
.9
5.12
5.
10
4.53
~
0'1
100
';0
80
>
0 s:: a;
0::: ,.... .....
0 ~
60
40
0
0 X •
Run
18
Run
19
Run
20
--t_
----
---
_! _
_ _
15
9°F
-------o
-------
• -
· --
--· -
x-.
-. --
-· __
1!8
L _
__
__
_ .
-.-_
-=---
--=--~.:.: :--.
:_ ~-__
:_ ~:.
.----
---~
_0
_
10
l°F
_
_ X
--
---~-
0 -
(0
---
--e
.
X
1 2
3 4
5 6
7 8
Hou
rs
into
Run
Figu
re
8 -
Eff
ect
of T
empe
ratu
re
~
0\
Hou
rs
Run
into
Oi
1
No.
Run
Type
2 7
SAE-
30
3 7
OE-
50
6 5
OE-
10
7 4
OE-
10
---}
11
4
OE-
10
--~
15
! 8
OE-
10
17
8 O
E-10
18
8
OE-
10
19
8 O
E-10
-;2
0
12
OE-
10
No.
of
Com
partm
ents
3 3 4 4 4 4 4 4 4 4
TABL
E IX
COM
PARI
SON
OF A
VERA
GE V
ALUE
S
Ave
rage
A
vera
ge
Ave
rage
A
vera
ge
Inle
t E
fflu
ent
Flow
Rat
e ~P 2
Tem
pera
ture
O
il C
one.
-Oil
Con
e.
gpm
1 b/i
n °F
pp
m pp
m
8.6
2.8
70
1383
32
7 8.
5 1.
42
70
484
49
9.2
2.18
70
10
80
554
9.9
2.2
70
1056
29
8 9.
9 2.
42
70
819
96
2.3
1.5
101
1270
29
2.
8 3.
03
101
877
110
2.8
2.6
101
738
117
2.6
3.8
148
945
125
2.7
4.5
159
1206
82
Ave
rage
%
Rem
oval
75.7
88
.5
47.2
43
87
.7
97.3
86
84
.2
85.3
92
.9
~
.........
48
and average removal for the successful runs. Runs 15 and 20 show
better average removal than runs 17, 18 and 19 which had lower oil
levels in the inlet stream.
The high inlet concentration may make it easier for the oil to
separate by gravity, as well as bi filtration/coalescence, as there
will be more oil droplets present than at the lower oil concentrations.
As the droplets coalesce and float upwards, they may collide and carry
with them smaller droplets, thus increasing the system efficiency.
A study of the flow pattern was made for various runs using dye
injection. An almost flat profile was exhibited in runs 6 and 7.
For run 17 and 18 the profile was flat in compartments one and two,
but a gradient developed in compartments three and four, with the velo
city being a maximum near the blocked off portion of the coalescer
plate. Nevertheless, the profile was deemed to be sufficiently flat
to permit a reasonable estimate to be made of the average residence
time in the device.
CHAPTER V
CONCLUSIONS
1. In a staged static device, using cotton terry for filters/
coalescers, no breakthrough was exhibited during 50 hours
of continuous operation under the conditions of this study.
2. Compared to simple gravity separation, 36% more oil was re-;
moved using terry towel filter/coalescers during tests at \ /
100°F and lower.
3. There was no noticeable effect on efficiency of the system
due to an increase in the water temperature. However, a
higher temperature required a higher driving force to mai"n
tain the same flow rate as in lower temperature tests.
RECOMMENDATIONS
1) A study is needed to establish a model to correlate per cent
oil removal to number of compartments, flow rate, temperature,
weave and thickness of the filter/coalescer elements.
2) Successive compartments should have tighter weaves. ~
3) A series of trials should be conducted on the waste water l r'
stream from cracker number 13 at El Paso Products Company, \
Odessa, Texas, to determine the efficiency of the system under\
actual working conditions.
4) When solids are present in the waste water, the use of an
"Auto/Klean"-type prefilter should be considered as it should
minimize plugging of the first filter/coalescer element. 49
TWS TECH LIBRARY
REFERENCES
1. Amant, L.S., Sr.: "The Petroleum Industry as It Affects ~1arine and Estuarine Ecology," Journal of Petroleum Technology, 24, 385-92 (Apr. 1972).
2. Anonymous: "Dillingham Plan Attacks Oil Spill Cleanup Problem," Chern. Engr. News, 48 (31), 34-37 (1970).
3. Bernhart, E. L.: "The Impact of Oily Materials on Activated Sludge Systems," API Project No. 12050DSH, HydroScience, Inc., Westwood, New Jersey (1971).
4. Duffy, S. R.: "Oil-water Separation Using Cotton Belts," M.S. Thesis, Texas Tech University, Lubbock, Texas (1971).
5. Gaines, T. H.: "Oil Pollution Control Efforts- Santa Barbara, California," Journal of Petroleum Technology, 22, 1511-14 (Dec., 1970).
6. Johnson, R. F., Manjrekar, T. G. and Halligan, J. E.: "Removal of Oil from Water Surfaces by Sorption on Unstructured Fibres," Environmental Science & Technology, 7 (5), 439-443 (1973). -
7. Lehr, W. E. and Leigh, J. T.: "Mechanical Equipment for the Cleanup of Oil Spills," Report No. 724103.1/1, United States Coast Guard Research and Development, Washington, D. C. (1971).
8. Lewicke, C. K.: "Cleaning Up Oil Spills Isn't Simple," Environmental Science & Technology, 7 (5), 398-400 (1973).
9. Manual on Disposal of Refinery Wastes: "Volume on Liquid Wastes," Chapters 1-9, API, Washington, D. C. (1969).
10. Manjrekar·, T. G.: "Fibrous Materials in Oil Slick Cleanup. Sorption on Structured Fibres," 172-194, Report No. D-71r~72-5, Textile Research Center, Texas Tech University, Lubbock, Texas (1972).
11. Milz, E. A.: "An Evaluation of Spill Control Equipment and Techniques," Paper presented at the 21st Annual Pipe Line Conference under the auspices of the API's Division of Transportation, Dallas, Texas (1970).
50
51
12. Mitchell, C. T., Anderson, E. K., Jones, L. G. and North, J. W.: 11 What Oil Does to Ecology, .. Journal WPCF, 42 (5}, Part 1, 812-18 (1970).
13. Oxenham, J. P.: 11 A Study of the Performance Characteristics ·of the Oleophilic Belt- Oil Scrubber, .. 309-317, Shell Pipe
Line Corporation, Research and Development Laboratory {1971).
14. Yu, T. S.: 11 A Proposed Shipboard Continuous Oil Polluting Control Process for Bilge Water, 11 Report No. 3191-A, Naval Ship Research and Development Laboratory, Annapolis, Md. ( 1969).
15. Yu, T. S. and Ventriglio, D. R.: 11 Shipboard Oil Pollution Control Systems for Ballast and Bilge Waters, A State-of-theArt Search, 11 Report No. Matlab 244, Naval Ship Research and Development Laboratory, Annapolis, Md. (1969).
